How to map a column of sample ID's to their respective filename

I have a dataframe which contains a column called sample_id amongst other metadata.

df <- data.frame(sample_id = c('x1', 'x2', 'x3', 'x4'))

I also have a list of files that contain their respective filenames which might not always have the same suffix.

files <- list('x1_001.txt', 'x2_003.txt', 'x4_abc.txt', 'x3_bg.txt')

I’d like to create a column in the data frame that greps the filename from the list of files and maps it to the respective sample_id.

However when I try to do that with df <- df %>% mutate(filename = grep(sample_id, files, value = TRUE) it doesn’t work.

Is there a function that has this capability or would I need to create something custom?

Thank you for any help.

df <- df %>% mutate(filename = grep(sample_id, files, value = TRUE)

>Solution :

It may be easier to extract the substring from the file names with sub and do a match with the ‘sample_id’ column and then reorder the files based on the numeric index

v1 <- unlist(files)
df$filename <- v1[match(df$sample_id, sub( "_.*", "", v1))]

-output

> df
  sample_id   filename
1        x1 x1_001.txt
2        x2 x2_003.txt
3        x3  x3_bg.txt
4        x4 x4_abc.txt